Angewandte Chemie International Edition in English

Cover image for Vol. 34 Issue 13‐14

July 31, 1995

Volume 34, Issue 13-14

Pages 1381–1525

Currently known as: Angewandte Chemie International Edition

    1. Cover Picture (Angew. Chem. Int. Ed. Engl. 13/14/1995)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199513791

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      The cover picture shows the bowl-shaped structure of the highly strained tricycle, dilithium acepentalenediide (C atoms blue–gray, H atoms white). Accordinly, the as yet unknown neutral hydrocarbon, acepentalene, should also have a bowl-shaped structure. In the solid state the dilithium acepentalenediide forms dimeric contact ion triplets, in which the convex side of the two dianion fragments point towards each other; the lithium counterions (silver) are coordinatively saturated with dimethoxyethane ligands (O atoms red). The computer graphics were generated by Dr. H. Michaelsen with a “ray tracing” program (Persistence of Vision 2.2) on a Power Challenge L (Silicon Graphics). More about this unusual dianion is reported by A. de Meijere, D. Stalke et al. on page 1492ff.

  1. Editorial

    1. Top of page
    2. Editorial
    3. Reviews
    4. Highlights
    5. Communications
    6. Book Reviews
    1. You have free access to this content
      Editorial (page 1381)

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199513811

  2. Reviews

    1. Top of page
    2. Editorial
    3. Reviews
    4. Highlights
    5. Communications
    6. Book Reviews
    1. My Search for Carbocations and Their Role in Chemistry (Nobel Lecture) (pages 1393–1405)

      Prof. Dr. George A. Olah

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199513931

      From the Organic Chemistry Institute of the Technical University of Budapest via the laboratories of the Dow Chemical Company (in Canada and the USA) and the Case Western Reserve University (Cleveland, Ohio), the path of George A. Olah finally led to the University of California in Los Angeles. At all research stations he pursued his major interest in carbocations, whose existence was still questioned by many at the beginning of his career. Olah gave the cations of carbon longer life to allow their observation in superacidic medium, and made the distinction between carbenium and carbonium ions. The reminiscences on an exciting bit of chemical history and a glimpse into his actual research make Olah's Nobel Lecture a must for every chemist.

    2. G Proteins and Regulation of Adenylate Cyclase (Nobel Lecture) (pages 1406–1419)

      Prof. Alfred G. Gilman

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514061

      How is the hormone-activated synthesis of the second messenger cyclic AMP regulated? Or, in more general terms, how does the interaction of an extracellular agonist with a receptor lead to intracellular enzyme activity when receptor and enzyme are not distinct macromolecules? The mediators are membrane-bound, guanine nucleotide binding regulatory proteins (G proteins). When the receptor is activated, G proteins dissociate into their subunits. These in turn activate or inhibit enzymes such as adenylate cyclases, which catalyze the synthesis of cyclic AMP. In these signal transmission processes G proteins act as molecular switches and amplifiers.

    3. Signal Transduction: Evolution of an Idea (Nobel Lecture) (pages 1420–1428)

      Prof. Martin Rodbell

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514201

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      Biological communication requires a complex meshwork of guanine nucleotide binding proteins (G proteins), receptors, effectors, and structure-forming extra- and intracellular components of cell membranes. The starting point for the development of the theory of cellular signal transduction was a very simple model (see scheme below). When a hormone H activates a receptor, a transducer (a G protein multimer) triggers the release of an enzyme as an intracellular reply.

  3. Highlights

    1. Top of page
    2. Editorial
    3. Reviews
    4. Highlights
    5. Communications
    6. Book Reviews
    1. Fullerene Model Compounds: Bowl-Shaped Aromatic Hydrocarbons and Cyclophane-Based Cage Molecules (pages 1429–1432)

      Dr. Rüdiger Faust

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514291

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      Fullerene fragments and other fullerene model compounds not only mimic certain aspects of the carbon spheres, but they are also fascinating compounds in their own right. Novel annelated polycyclic arenes such as 1 have been synthesized, whose anions could potentially form endo- and exohedral complexes with metal cations. Recently the hydrocarbon cage compound 2 (C60H60) was found to complex Ag+ ions selectively.

    2. Progress in Oligosaccharide Synthesis through a New Orthogonal Glycosylation Strategy (pages 1432–1434)

      Prof. Dr. Hans Paulsen

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514321

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      Two monosaccharide building blocks, two reagents, and four steps are all it takes to synthesize heptasaccharide 1 according to a new strategy by T. Ogawa et al. In view of the tremendous arsenal of glycosylation reactions, this new method should inspire other related approaches.

  4. Communications

    1. Top of page
    2. Editorial
    3. Reviews
    4. Highlights
    5. Communications
    6. Book Reviews
    1. [WL(NO)(O)(CH3)]— An Unusual Nitrosyltungsten Complex (pages 1435–1437)

      Dr. Jochen Böhmer, Prof. Dr. Karl Wieghardt and Dr. Bernhard Nuber

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514351

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      A strong π acceptor and a strong π donor—NO and O ligands, respectively—coordinated cis to the same metal atom are present in the complex 1. The NO stretching frequency of the linear W[BOND]NO unit occurs at extremely low wavenumber (1433 cm−1). The red complex 1 forms by reduction of [WL(CO)2(NO)]+ to [WL(NO)(CO)(Me)] (L = heterocycle) followed by reaction with O2.

    2. Synthesis of Belt Cyclophanes (pages 1437–1439)

      Prof. Dr. Herbert Meier and Dipl.-Chem. Klaus Müller

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514371

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      The photocyclodimerization of areno-condensed [18]annulenes with alkoxy side chains leads to novel beltlike cyclophanes (schematic representation on the right). For derivatives with certain substitution patterns the “monomers” form columnar, photoreactive liquid crystals.

    3. Silacyclopropene: Generation by High-Vacuum Flash Pyrolysis and Matrix-Spectroscopic Identification (pages 1439–1441)

      Prof. Dr. Günther Maier, Dipl.-Chem. Harald Pacl and Dr. Hans Peter Reisenauer

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514391

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      Since the first synthesis of a silacyclopropene, efforts have been made to prepare the unsubstituted parent compound 3. This goal has finally been achieved: Pyrolytic elimination of trimethylsilane from 1 initially leads to the silanediyl 2, which cyclizes to 3.

    4. First Steps Towards Ordered Monolayers of Ligand-Stabilized Gold Clusters (pages 1442–1443)

      Dipl.-Chem. Stefanie Peschel and Prof. Dr. Günter Schmid

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514421

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      Through interactions between sulfonic groups of the water-soluble Au cluster C and imino groups of a poly(ethylenimine) layer B on a mica surface A, this cluster could be attached for the first time in a largely ordered form as a monolayer. Now, for example, electronic transitions of quantum dots (cluster cores) separated by ligand shells can be investigated.

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    5. Self-Assembly of a Ferromagnetically Coupled Manganese(II) Tetramer (pages 1443–1446)

      Dr. Angelo J. Amoroso, Dr. John C. Jeffery, Peter L. Jones, Prof. Jon A. McCleverty, Dr. Peter Thornton and Dr. Michael D. Ward

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514431

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      π-Stacking interactions between adjacent aromatic ligand fragments of L separated by approximately 3.4 Å provides a pathway for weak ferromagnetic coupling in the tetramer [Mn4L4](PF6)4 (1). The cavity of L is too large for a single MnII ion; instead the tetramer 1 comprises a Mn4 tetrahedron, with a ligand L attached to each triangular face. In the self-assembly of 1, eight components are combined under the formation of 24 Mn[BOND]N bonds to give a complicated structure.

    6. The Two-Dimensional Network Structure and Metamagnetic Properties of the 2:1 Complex of [Mn(3-MeOsalen)(H2O)]ClO4 and K3[Fe(CN)6] (pages 1446–1448)

      Hitoshi Miyasaka, Prof. Naohide Matsumoto, Hisashi Ōkawa, Dr. Nazzareno Re, Dr. Emma Gallo and Prof. Carlo Floriani

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514461

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      Cyclic tetrameric units (··Mn-NC-Fe-CN··)4 (depicted on the right) construct the two-dimensional network of the title compound. The layers thus formed are linked together by van der Waals contacts. The compound displays metamagnetism: ferromagnetic coupling is observed within layers and antiferromagnetic coupling between layers.

    7. Macrobicyclic Titanium(IV) Complexes with C3-Symmetric Synthetic Peptides (pages 1449–1451)

      Dipl.-Chem. Kay Severin, Prof. Dr. Wolfgang Beck, Dipl.-Chem. Gunter Trojandt, Dr. Kurt Polborn and Prof. Dr. Wolfgang Steglich

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514491

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      Preorganization by intramolecular hydrogen bonds facilitates the synthesis of macrobicyclic TiIV complexes with ring sizes up to 32 atoms (shown schematically below). C3-symmetric peptide bundles, each fixed by a central nitrogen atom, serve as ligands. AS [DOUBLE BOND] α-amino acids (Gly, Leu, Phe, Val).

    8. Rapid Water Diffusion in a Cage-Type Crystal Lattice: β-Cyclodextrin Dodecahydrate (pages 1452–1453)

      Dr. Thomas Steiner, Aida M. Moreira da Silva, Prof. Dr. José J. C. Teixeira-Dias, Prof. Dr. Jörn Müller and Prof. Dr. Wolfram Saenger

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514521

      Despite the absence of water channels, H/D and Hmath imageO/Hmath imageO exchange experiments show that water molecules diffuse rapidly through the crystal lattice of β-cyclodextrin · 12H2O (CD). Exchange takes place in minutes and follows first-order kinetics. This is explained by the structural fluctuations of the β-CD molecules, which became apparent in crystallographic studies and in computer simulations.

    9. X-Ray Diffraction Evidence for a Cyclohexatriene Motif in the Molecular Structure of Tris(bicyclo[2.1.1]hexeno)benzene: Bond Alternation after the Refutation of the Mills–Nixon Theory (pages 1454–1456)

      Prof. Dr. Hans-Beat Bürgi, Dr. Kim K. Baldridge, Prof. Kenneth Hardcastle, Natia L. Frank, Dr. Peter Gantzel, Prof. Jay S. Siegel and Dr. Joseph Ziller

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514541

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      Cyclohexatriene lost, cyclohexatriene regained! Recently the Mills–Nixon postulate concerning the structure of benzene derivatives was recognized to be invalid. A new view on strain-induced bond localization in benzene led to the design and synthesis of tris(bicyclo[2.1.1]hexeno)benzene (1), which shows significant distortion toward a cyclohexatriene geometry.

    10. Architectural Control in “Living” Free Radical Polymerizations: Preparation of Star and Graft Polymers (pages 1456–1459)

      Dr. Craig J. Hawker

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514561

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      The use of multifunctional initiators such as 1 in a novel “living” free radical polymerization process allows the preparation of low polydispersity star and graft copolymers with accurate control over the molecular weight of each arm.

    11. A Novel Chainlike Heteropolyanion Formed by Keggin Units: Synthesis and Structure of (ET)8n[PMnW11O39]n · 2nH2O (pages 1460–1462)

      José Ramón Galán-Mascarós, Carlos Giménez-Saiz, Dr. Smaïl Triki, Dr. Carlos J. Gómez-García, Prof. Dr. Eugenio Coronado and Dr. Lahcène Ouahab

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514601

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      Novel, polymeric linear chains of Keggin polyoxometalate units PMnW11O39 linked through Mn-O-W bridges (see picture below) are present in the structure of the title compound 1. The chains alternate with layers of the organic donor bis(ethylenedithio)tetrathiafulvalene (ET). Compound 1 promises interesting material properties resulting from the combination of localized magnetic moments with delocalized electrons.

    12. A Silicon Strand of More than 7 Å in Diameter in Ba2Eu3Si7 (pages 1462–1464)

      Christina Häußermann and Prof. Dr. Reinhard Nesper

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514621

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      Planar-coordinated silicon atoms dominate the new one-dimensional Zintl anion math image[Simath image] that occurs in the ternary compound Ba2Eu3Si7. Although the anion is isoelectronic with Emath image (E = P, As), it has a completely different structure (depicted here), which most likely depends on the cation environment.

    13. The Role of Dehydroalanine in Catalysis by Histidine Ammonia Lyase (pages 1464–1465)

      Dr. Martin Langer, Dr. Andrea Pauling and Prof. Dr. János Rétey

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514641

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      Not the α-amino group but the 5-position of the imidazole ring functions as a nucleophile towards the prosthetic dehydroalanine residue in the deamination of histidine catalyzed by histidine ammonia lyase (HAL) [Eq. (a)]. The results discussed here strongly support this proposal.

    14. Solubilized Derivatives of C195 and C260: The First Members of a New Class of Carbon Allotropes Cn(60 + 5) (pages 1466–1469)

      Lyle Isaacs, Paul Seiler and Prof. François Diederich

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514661

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      Cyclic fullerene–acetylene hybrids, a tris(fullerene)-cyclo-C15 (1) and a tetrakis(fullerene)-cyclo-C20 compound (2), were synthesized by Eglinton–Glaser coupling. Both oligomers fragment under MALDI-TOF MS conditions to give sequential loss of the C60 units, which potentially provides controlled access to the hitherto unknown free ions cyclo-Cmath image and cyclo-Cmath image. X = (EtO2CCH2O2C)2C.

    15. First Synthesis of 2H-Azepine (pages 1469–1471)

      Dipl.-Chem. Dieter Hamprecht, Dr. Kurt Polborn and Prof. Dr. Wolfgang Steglich

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514691

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      Highly volatile and unstable in the pure form, the 2H-azepine 1 has been synthesized for the first time. This compound is a “spin-off” from work on the chemistry of azepine alkaloids, which occur in the mushroom Chalciporus piperatus. In addition, a bicyclic product of a surprising Diels–Alder reaction forms in the cyclization step.

    16. Lyotropic Phases Formed by “Molecular Bottlebrushes” (pages 1472–1474)

      Dr. Matthias Wintermantel, Dr. Karl Fischer, Markus Gerle, Dr. Roland Ries, Prof. Dr. Manfred Schmidt, Prof. Dr. Kanji Kajiwara, Dr. Hiroshi Urakawa and Dr. Isao Wataoka

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514721

      Extremely stiff macromolecules in the form of “hairy rods” or more precisely “molecular bottlebrushes” (without a handle) are easily accessible by the polymerization of polymacromonomers. As anticipated from their high degree of stiffness, these molecules form lyotropic, liquid-crystalline phases, although they consist of “commodity” monomers like styrene and methylacrylate.

    17. Enhancement of Catalytic Activity for Hydroformylation of Methyl Acrylate by Using Biphasic and “Supported Aqueous Phase” Systems (pages 1474–1476)

      Dipl.-Chem. Georges Fremy, Dr. Eric Monflier, Dr. Jean-François Carpentier, Prof. Dr. Yves Castanet and Prof. Dr. André Mortreux

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514741

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      High activities and selectivities are obtained for the rhodium-catalyzed hydroformylation of methyl acrylate in biphasic and “supported aqueous phase” (SAP) systems [Eq. (a)]. The biphasic system Rh/P(C6H4SO3Na)31 is twice as active as the classic Rh/PPh3 combination (homogeneous system), and the SAP system Rh/P(C6H4SO3Na)3/SiO22 is twenty times more active.

    18. A Remarkable Effect of Silyl Substitution on Electrocyclization of Vinylallenes (pages 1476–1477)

      Prof. Masahiro Murakami, Hideki Amii, Kenichiro Itami and Prof. Yoshihiko Ito

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514761

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      The kinetics and thermodynamics of the electrocyclization of vinylallenes are favorably influenced when a silyl substituent is introduced into the open-chain compound. A series of vinylallenes containing a silyl group at the vinyl terminus (1) gave good yields of the corresponding cyclobutenes 2 when heated at reflux in xylene. A theoretical explanation for this observation remains elusive.

    19. C3-Symmetric Hexakis(trimethylsilyl)[7]phenylene[“Tris(biphenylenocyclobutadieno)cyclohexatriene”], a Polycyclic Benzenoid Hydrocarbon with Slightly Curved Topology (pages 1478–1481)

      Prof. Roland Boese, Adam J. Matzger, Dr. Debra L. Mohler and Prof. Dr. K. Peter C. Vollhardt

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514781

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      In four steps and a yield of 14%, the [7]phenylene 1 has been prepared from hexakis(trimethylsilylethynyl)-benzene. The trigonal 1 is not planar but slightly curved, and the unit cell features two molecules, staggered and offset, facing each other in a concave–concave arrangement.

    20. Photoinduced Valence Tautomerism in Cobalt Complexes Containing Semiquinone Anion as Ligand: Dynamics of the High-Spin [CoII(3,5-dtbsq)2] to Low-Spin [CoIII(3,5-dtbsq)(3,5-dtbcat)] Interconversion (pages 1481–1483)

      David M. Adams, Bulang Li, Prof. John D. Simon and Prof. David N. Hendrickson

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514811

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      Picosecond laser-flash photolysis is employed to study intramolecular electron transfer and spinstate interconversion in a valence tautomeric cobalt complex. The CoIII form 1 of the complex is photoexcited to the high-spin CoII(semiquinone anion)2 form, whereupon relaxation back to the low-spin CoIII(semiquinone anion)(o-catecholate) state is monitored.

    21. Burial of Hydrocarbon Causes Cooperative Enhancement of Electrostatic Binding (pages 1483–1485)

      Gary J. Sharman, Dr. Mark S. Searle, Bellinda Benhamu, Dr. Patrick Groves and Dr. Dudley H. Williams

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514831

      The introduction of alanine methyl groups in adjacent positions on a peptide ligand results in a cooperative enhancement of electrostatic binding from the burial of hydrocarbon. This observation may explain why larger changes in free energy occur when hydrocarbon substituents are buried in a molecular recognition site than can be accounted for by the solvent transfer model (classical hydrophobic effect).

    22. Novel, Blue-Transparent Frequency Doublers Based on 1,8-Di(hetero)arylnaphthalenes (pages 1485–1488)

      Dipl.-Chem. André Bahl, Priv.-Doz. Dr. Walter Grahn, Dipl.-Chem. Stefan Stadler, Dipl.-Phys. Franz Feiner, Dr. Grant Bourhill, Prof. Dr. Christoph Bräuchle, Dipl.-Chem. Axel Reisner and Prof. Dr. Peter G. Jones

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514851

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      Consecutive Suzuki coupling provides a general method for preparing 1,8-diarylnaphthalenes such as 2 (A = acceptor, D = donor) from the boronic acid 1. Noncovalent π–π interactions render them markedly more NLO-active than the 1,5-isomers (which absorb at longer wavelength) and thus fascinating alternatives to the best, classical, blue-transparent frequency doublers.

    23. The Active Sites of the Native Cytochrome-c Oxidase from Bovine Heart Mitochondria: EXAFS-Spectroscopic Characterization of a Novel Homobinuclear Copper Center (CuA) and of the Heterobinuclear Fea3-CuB Center (pages 1488–1492)

      Prof. Dr. Gerald Henkel, Dipl.-Chem. Arnd Müller, Dr. Stefan Weissgräber, Prof. Dr. Gerhard Buse, Dr. Tewfik Soulimane, Dr. Guy C. M. Steffens and Dr. Hans-Friedrich Nolting

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514881

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      A novel homobinuclear Cu2 complex describes best the CuA center of the cytochrome-c oxidase from bovine heart mitochondria according to EXAFS investigations. In this complex, which contains two terminal histidine residues, two cysteine sulfur bridges, and probably a bridging oxygen donor function, the Cu[BOND]Cu distance of 2.46 Å is very short. The structure of the Fea3-CuB center was likewise determined.

    24. Dilithium Acepentalenediide: An Unusual Dimer of Contact Ion Triplets with Bowl-Shaped Dianions (pages 1492–1495)

      Dipl.-Chem. Rainer Haag, Dipl.-Chem. Roland Fleischer, Priv.-Doz. Dr. Dietmar Stalke and Prof. Dr. Armin de Meijere

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514921

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      Pure 4,7-bis(trimethylstannyl)dihydroacepentalene 1 can be transformed cleanly into dilithium acepentalenediide 2 by treatment with methyllithium. In the crystal 2 adopts an interesting dimeric structure in which the convex sides of the two bowl-shaped dianionic fragments face each other.

    25. Electron Transfer and Polar Reactions of Cyclizable Anion Radicals: Structural Consequences of Orbital Selection Rules and Chain-Length Constraints (pages 1495–1497)

      G. Narahari Sastry, Dr. A. Chandrasekhar Reddy and Prof. Dr. Sason Shaik

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514951

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      Transition states for electron transfer with strong bonding interactions are reported in the reactions of anion radicals 1 (n = 2,3). The heights of the activation barriers for the substitution and electron transfer pathways leading to 2 and 3, respectively, are a function of the length n of the methylene chain. This is predicted on the basis of orbital selection rules derived from valence bond configuration mixing analysis, and confirmed here by ab initio calculations.

    26. New Nonlinear Optical Materials: Expedient Topotactic Self-Assembly of Acentric Chromophoric Superlattices (pages 1497–1499)

      Dr. Wenbin Lin, Dr. Shlomo Yitzchaik, Weiping Lin, Amit Malik, Mary K. Durbin, Andrew G. Richter, Prof. George K. Wong, Prof. Pulak Dutta and Prof. Tobin J. Marks

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514971

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      High structural regularity, second-order nonlinear susceptibility, and thermal stability characterize the self-assembled stilbazolium chromophoric multilayers (the structure obtained after the first cycle is shown schematically on the right). A topotactic approach for the stilbazolium chromophore deposition has resulted in conceptually attractive, artificial, acentric assemblies for organic second-order nonlinear materials.

    27. Structure Organization of Aluminosilicate Polyanions with Surfactants: Optimization of Al Incorporation in Aluminosilicate Mesostructural Materials (pages 1499–1502)

      Dr. Guoyi Fu, Prof. Dr. Colin A. Fyfe, Dr. Wilhelm Schwieger and Dr. George T. Kokotailo

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199514991

      Hexagonal and lamellar aluminosilicate mesostructures with a Si/Al ratio close to 1 have been obtained by a new two-step synthetic route. The precursor aluminosilicate Al4Si4O12(OH)math image and the surfactants organize into mesophasic precipitates when the corresponding solutions are mixed together. Further condensation and structure ordering of the precipitated phases can then be achieved by vapor-phase treatment or refluxing isopropyl alcohol treatment leading to mesostructural materials.

    28. One-Electron Redox Reactions of CoASH Esters in Anaerobic Bacteria—A Mechanistic Proposal (pages 1502–1506)

      Prof. Dr. Wolfgang Buckel and Prof. Dr. Reinhart Keese

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199515021

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      Ketyl intermediates in unusual enzymatic reactions in anaerobic bacteria may possibly be generated by one-electron reductions of thioesters (coenzyme-A esters). One example is the reversible syn-dehydration of (R)-2-hydroxyglutaryl-CoA via 1 to give (E)-glutaconyl-CoA.

    29. Synthesis and Structure of the First Sulfur-Bridged [1]Ferrocenophane (pages 1506–1508)

      Dr. John K. Pudelski, Derek P. Gates, Ron Rulkens, Dr. Alan J. Lough and Prof. Ian Manners

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199515061

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      A sulfur atom is the smallest bridging element yet incorporated into a [1]ferrocenophane. This is demonstrated by the synthesis of the purple, crystalline [1]ferrocenophane 1 (structure depicted on the right). The 31.05(10)° tilt angle between the planes of the cyclopentadienyl rings is the largest for any iron group [n]metallocenophane.

    30. Synthesis and X-Ray Powder Structure of a Novel Porous Uranyl Phenylphosphonate Containing Unidimensional Channels Flanked by Hydrophobic Regions (pages 1508–1510)

      Dr. Damodara M. Poojary, Daniel Grohol and Prof. Dr. Abraham Clearfield

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199515081

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      Stacking interactions between phenyl groups hold the unidimensional channels in the structure of 1 together (shown on the right). The structure was determined from X-ray powder diffraction data, which revealed that the channel opening is more than 12 Å and the free space approximately 7 Å in diameter.

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    31. Hydrocarbon Activation with Metal Halides: Catalysis of the Jacobsen Rearrangement by (ZrCl4)n in the Presence of Aromatic Hydrocarbons (pages 1510–1512)

      Dr. Euro Solari, Fabrizio Musso, Dr. Richard Ferguson, Prof. Dr. Carlo Floriani, Prof. Dr. Angiola Chiesi-Villa and Dr. Corrado Rizzoli

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199515101

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      Extremely mild conditions suffice for the ZrCl4-mediated rearrangement of permethylated arenes at room temperature in halogenated solvents. This reaction, better known as the Jacobsen reaction, was previously observed only in concentrated sulfuric acid. In the presence of durene, (ZrCl4)n is surprisingly soluble. The active species in the reaction of C6Me6 is shown on the right.

    32. Nonheme Iron Centers in Oxygen Activation: Characterization of an Iron(III) Hydroperoxide Intermediate (pages 1512–1514)

      Dr. Marcel Lubben, Dr. Auke Meetsma, Elizabeth C. Wilkinson, Prof. Ben Feringa and Prof. Lawrence Que Jr.

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199515121

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      A new pentadentate nitrogen ligand facilitates the synthesis of a low-spin iron(II) complex, which reacts with H2O2 at low temperature to form the transient purple complex 1. Complex 1 was formulated as an FeIIIOOH complex, the first synthetic example of such a species to be characterized by electrospray ionization mass spectrometry. Furthermore, 1 oxidizes cyclohexane efficiently, thus supporting the notion that an FeIIIOOH moiety can participate in oxygen activation mechanisms of nonheme iron enzymes.

    33. The pH-Dependent Synthesis and Structural Study of Dimer and Cyclic Trimer Complexes of 9-Methyl- or 9-Ethylhypoxanthine Nucleobases with (η5-Pentamethylcyclopentadienyl)-rhodium Aqua Complexes (pages 1514–1517)

      Dr. Hong Chen, Dr. Marilyn M. Olmstead, Dr. David P. Smith, Dr. Marcos F. Maestre and Dr. Richard H. Fish

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199515141

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      η1(N1)- and η2(N7,O6)-coordination of the Rh atoms by 9-ethylhypoxanthin (9-EH) is evident in the cyclic trimer 1 (see picture). This is formed from [(C5Me5RhCl2)2], AgOSO2CF3, and 9-EH in water at pH 6.1. An entirely different coordination arises at pH 10.2 for the complex with the ligand 9-methyl-hypoxanthin (9-MH): in the dimer 2 the metal atoms are η1(N1)-coordinated. The formation of dramatically different structures at various pH values could be explained by the changes in the nucleophilicity of the N7, O6, and N1 binding sites.

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    34. Single-Crystal X-Ray Structure of the Metastable Aryne Precursor Tetrafluorophenyllithium and of 1,2,3,4-Tetrafluorobenzene (pages 1517–1519)

      Dr. Thomas Kottke, Dr. Kuangsen Sung and Prof. Dr. Richad J. Lagow

      Version of Record online: 22 DEC 2003 | DOI: 10.1002/anie.199515171

      Do intramolecular Li[BOND]F interactions affect the reactivity of aryne precursors? This was the key question for structural studies of lithiated and nonlithiated tetrafluorobenzene. No correlation between Li[BOND]F distances and the ease of LiF elimination exists, and the lengths of the Caryl[BOND]F bonds in the lithiated compound are less affected by Li[BOND]F interactions than by the “anionic” character of the benzene ring.

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